The type species, Eshanosaurus deguchiianus, was described by Xu, Zhao, and Clark in 2001. The authors here place Eshanosaurus in the therizinosaur family on the basis of three distinct synapomorphies. That makes it the earliest known Coelurosaur, and an advanced maniraptor living long before Archaeopteryx.
Mistakes have been made in Paleontology in the past when fossil teeth and jaws have been assigned to advanced dinosaur groups and later reassigned to more primitive reptiles (see Lisboasaurus). Especially troublesome for Eshanosaurus is that it was found below numerous fossils of Lufengosaurus, a prosauropod which can very closely resemble a therizinosaur. The authors are aware of this, and exclude this possibility as rigorously as they can.
A NEW THERIZINOSAUR FROM THE LOWER JURASSIC LOWER LUFENG FORMATION OF YUNNAN, CHINA XING XU, XIJIN ZHAO, and JAMES M. CLARK Journal of Vertebrate Paleontology 21(3):477–483, September 2001 q 2001 by the Society of Vertebrate Paleontology